Tundra Loses Carbon with Rapid Permafrost Thaw

Artistic interpretation of tundra carbon dioxide (CO2) uptake and loss with permafrost thaw and accounting for CO2 dynamics in the summer and winter.

The Science

Frozen in permafrost soil, northern latitudes store almost twice as much carbon as is currently in the atmosphere. Rapid Arctic warming is expected to expose previously frozen soil carbon to microbial decomposition and increase carbon dioxide release. The impact on the carbon dioxide balance is, however, unclear. Why? Because warmer temperatures and nutrients released from thawing permafrost increase plant growth and could offset carbon dioxide losses. We examined the effect of warmer air and the effect of warmer soil and permafrost thaw on tundra ecosystem carbon dioxide. Seven years of experimental study show that summer plant growth did not, in the longer term, take up as much carbon as was lost by soil warming and permafrost.

The Impact

Models and observations currently disagree over how Arctic warming will affect the carbon dioxide balance of tundra ecosystems. Few studies combine warmer air and permafrost thaw to evaluate the ecosystem carbon dioxide balance. This work shows that tundra carbon dioxide uptake and loss responded much more strongly to permafrost thaw than to warmer air alone. Rapid permafrost thaw did initially stimulate carbon dioxide uptake during the summer. However, uptake leveled off with very deep thaw. In all years of the experiment, summer carbon dioxide uptake was insufficient to offset year-round carbon dioxide losses.

Summary

Seven years of experimental air and soil warming in tundra show that soil warming and permafrost thaw had a much stronger effect on carbon balance than air warming. Permafrost thaw initially stimulated greater summer carbon dioxide uptake than carbon dioxide loss; however, the initial increases were not sustained. As thaw continued to progress, summer carbon dioxide uptake and carbon dioxide loss leveled off. Leveling off carbon dioxide uptake and release could be explained by the slowing of plant growth and greater soil saturation as thaw caused the ground surface to collapse. The complex interactions between permafrost thaw, plant growth, and soil moisture could be captured mathematically by a quadratic relationship showing that the effect of thaw on carbon dioxide uptake and loss changed over time. Models and measurements used to estimate carbon dioxide losses during the winter found that the tundra was losing carbon dioxide on an annual basis, even during those summers when thaw stimulated high plant growth and carbon dioxide uptake.

Funding

This work was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Terrestrial Ecosystem Science Program (DE-SC0006982 and DE-SC0014085); National Science Foundation CAREER program (0747195); National Science Foundation Bonanza Creek Long-Term Ecological Research program (1026415); National Science Foundation Office of Polar Programs (1203777); and National Parks Inventory and Monitoring Program.

Filters

Using X-ray techniques, scientists are developing an analysis tool that can more accurately predict how sulfur compounds in a batch of crude oil might corrode equipment- an important safety issue for the oil industry.

A University of Wisconsin-Madison physicist and his colleagues are turning IceCube, the world's most sensitive neutrino telescope, to the task of helping demystify powerful pulses of radio energy generated up to billions of light-years from Earth.

Eat too much without exercising and you'll probably put on a few pounds. As it turns out, plant leaves do something similar. In a new study at the U.S. Department of Energy's Brookhaven National Laboratory, scientists show that retaining sugars in plant leaves can make them get fat too. In plants, this extra fat accumulation could be a good thing.

In a recent experiment conducted at the Department of Energy's SLAC National Accelerator Laboratory, a research team used bright, ultrafast X-ray pulses from SLAC's X-ray free-electron laser to create a high-speed movie of a fluorescent protein in action. With that information, the scientists began to design a marker that switches more easily, a quality that can improve resolution during biological imaging.

In a study published Sept. 20 in Nature, UChicago and Cornell University researchers describe an innovative method to make stacks of semiconductors just a few atoms thick. The technique offers scientists and engineers a simple, cost-effective method to make thin, uniform layers of these materials, which could expand capabilities for devices from solar cells to cell phones.

In cancer cells, a membrane transport protein called P-glycoprotein, or Pgp, actively pumps anticancer drugs out of the cell, contributing to multidrug resistance. Recently, a team led by computational biophysicist Emad Tajkhorshid from the University of Illinois at Urbana-Champaign (UIUC) used the Titan supercomputer to uncover new details about Pgp that could help the drug discovery community manipulate Pgp function.

Prof. Daniel Zajfman's universal ion trap cools to a tenth of a degree above absolute zero. The new method does not depend on the type or the weight of the ion and, thus, might be used to investigate the properties of large biological molecules or nanoparticles, among other things.

Whispering gallery mode resonators rely on a phenomenon similar to an effect observed in circular galleries, and the same phenomenon applies to light. When light is stored in ring-shaped or spherical active resonators, the waves superimpose in such a way that it can result in laser light. This week in APL Photonics, investigators report a new type of dye-doped WGM micro-laser that produces light with tunable wavelengths.

Filters

Kasper Kjaer is the winner of the inaugural LCLS Young Investigator Award given by the Users Executive Committee of the Linac Coherent Light Source (LCLS). The prize recognizes scientists in the early stages of their career for exceptional research performed with the LCLS X-ray free-electron laser at the Department of Energy's SLAC National Accelerator Laboratory.

The U.S. Department of Commerce announced that UTEP has been awarded a $500,000 grant to create and expand cluster-focused proof-of-concept and commercialization programs through the Economic Development Administration's (EDA) Regional Innovation Strategies (RIS) program.

Two Berkeley Lab teams will receive DOE funding to develop near-term quantum computing platforms and tools to be used for scientific discovery in the chemical sciences. One team will develop novel algorithms, compiling techniques and scheduling tools, while the other team will design prototype four- and eight-qubit processors to compute these new algorithms.

As part of the Department of Energy's (DOE's) commitment to building cyber-resilient energy delivery systems, a new project led by Lawrence Berkeley National Laboratory will develop tools to detect and counter cyber attacks on the grid via solar panels.

Many of the DOE Joint Genome Institute's selected 2018 Community Science Program proposals aim to utilize multiple genomic and analytical capabilities, along with scientific expertise, to users focused on the underlying mechanisms involved in bioenergy generation and biogeochemical processes.

West Virginia University professors Paul Ziemkiewicz, Shikha Sharma and Tim Carr will present research on technology in the shale industry at the Shale Insight Conference on Wednesday, Sept. 27 in Pittsburgh, Pa.

A new high-performance computing initiative announced this week by the U.S. Department of Energy will help U.S. industry accelerate the development of new or improved materials for use in severe environments.

Researchers at Wayne State University led by Nathan Fisher, associate professor of computer science in the College of Engineering, received a $1.2 million grant from the National Science Foundation to address the need for effective, integrative battery operating systems that provide sustained and reliable power.